Objective:To explore the differences of cortical responses to unilateral upper limb training (UULT) in subacute stroke patients with different motor-evoked potentials (MEPs).Methods:A cross-sectional study was performed; 33 subacute stroke patients accepted UULT were recruited from Center of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University from August 2023 to August 2024. Transcranial magnetic stimulation was used to assess MEPs, and functional near-infrared spectroscopy (fNIRS) was used to record hemodynamic changes in bilateral primary motor cortex (M1), pre-motor cortex/supplementary motor area (PMC/SMA), and posterior parietal cortex (PPC) during the resting state and UULT task state. Wavelet coherence analysis and Granger causality analysis were used to determine the strengths of functional connectivity (FC) and effective connectivity (EC) between brain regions.Results:Among the 33 patients, 16 were assigned to an absent MEP (MEP -) group and 17 into a present MEP (MEP +) group (MEP amplitude: [310±200] μV). In the MEP - group, compared with those during the resting state, FC of ipsilesional M1 with contralesional PPC, contralesional M1, ipsilesional PPC, contralesional PMC/SMA and ipsilesional PMC/SMA during the task state (0.64±0.14 vs. 0.48±0.12, 0.63±0.14 vs. 0.45±0.10, 0.70±0.14 vs. 0.56±0.12, 0.56±0.13 vs. 0.39±0.15, 0.61±0.13 vs. 0.44±0.14), and FC between the ipsilesional PMC/SMA and ipsilesional PPC during the task state (0.71±0.12 vs. 0.61±0.09) were significantly decreased ( P<0.0033); compared with that during the resting state, EC from the ipsilesional PPC to the ipsilesional PMC/SMA during the task state (0.15±0.07 vs. 0.25±0.18) was significantly increased ( P<0.05). In the MEP + group, compared with that during the resting state, FC of the ipsilesional M1 with contralesional M1 and ipsilesional PPC during the task state (0.81±0.08 vs. 0.70±0.14, 0.78±0.08 vs. 0.68±0.13) was significantly decreased ( P<0.0033); compared with that during the resting state, EC from contralesional M1 to ipsilesional M1 during the task state (0.11±0.10 vs. 0.15±0.10) was significantly increased ( P<0.05). No significant differences were noted in changes of FC strength between resting state and UULT task state across brain regions when comparing the MEP - and MEP + groups ( P>0.0033). Conclusion:MEP - subacute stroke patients exhibit extensive bilateral cortical response during the UULT task state, whereas MEP + patients show limited cortical response, which indicate that rehabilitation training strategy in MEP + patients needs to be adjusted.

Objective:To explore the differences of cortical responses to unilateral upper limb training (UULT) in subacute stroke patients with different motor-evoked potentials (MEPs).Methods:A cross-sectional study was performed; 33 subacute stroke patients accepted UULT were recruited from Center of Rehabilitation Medicine, Zhujiang Hospital, Southern Medical University from August 2023 to August 2024. Transcranial magnetic stimulation was used to assess MEPs, and functional near-infrared spectroscopy (fNIRS) was used to record hemodynamic changes in bilateral primary motor cortex (M1), pre-motor cortex/supplementary motor area (PMC/SMA), and posterior parietal cortex (PPC) during the resting state and UULT task state. Wavelet coherence analysis and Granger causality analysis were used to determine the strengths of functional connectivity (FC) and effective connectivity (EC) between brain regions.Results:Among the 33 patients, 16 were assigned to an absent MEP (MEP -) group and 17 into a present MEP (MEP +) group (MEP amplitude: [310±200] μV). In the MEP - group, compared with those during the resting state, FC of ipsilesional M1 with contralesional PPC, contralesional M1, ipsilesional PPC, contralesional PMC/SMA and ipsilesional PMC/SMA during the task state (0.64±0.14 vs. 0.48±0.12, 0.63±0.14 vs. 0.45±0.10, 0.70±0.14 vs. 0.56±0.12, 0.56±0.13 vs. 0.39±0.15, 0.61±0.13 vs. 0.44±0.14), and FC between the ipsilesional PMC/SMA and ipsilesional PPC during the task state (0.71±0.12 vs. 0.61±0.09) were significantly decreased ( P<0.0033); compared with that during the resting state, EC from the ipsilesional PPC to the ipsilesional PMC/SMA during the task state (0.15±0.07 vs. 0.25±0.18) was significantly increased ( P<0.05). In the MEP + group, compared with that during the resting state, FC of the ipsilesional M1 with contralesional M1 and ipsilesional PPC during the task state (0.81±0.08 vs. 0.70±0.14, 0.78±0.08 vs. 0.68±0.13) was significantly decreased ( P<0.0033); compared with that during the resting state, EC from contralesional M1 to ipsilesional M1 during the task state (0.11±0.10 vs. 0.15±0.10) was significantly increased ( P<0.05). No significant differences were noted in changes of FC strength between resting state and UULT task state across brain regions when comparing the MEP - and MEP + groups ( P>0.0033). Conclusion:MEP - subacute stroke patients exhibit extensive bilateral cortical response during the UULT task state, whereas MEP + patients show limited cortical response, which indicate that rehabilitation training strategy in MEP + patients needs to be adjusted.